Method for manufacturing transmission screen and transmission screen

ABSTRACT

A method of producing a transmissive screen having a structure including light-absorption-material patterns formed on locations corresponding to locations of lens members, which are provided side by side on a light-transmissive substrate, and to locations of boundary portions between the corresponding lens members. In the method, lens compositions are discharged onto and are caused to land on the light transmissive substrate, and, by drops of the lens compositions, very small lens members or precursors thereof are formed. It is possible to provide a method of producing a transmissive screen, which makes it possible to realize at a low cost a bright transmissive screen which has high contrast ratio and which can display a high-quality image having no moiré and no speckles.

TECHNICAL FIELD

[0001] The present invention relates to a projection screen technology,and, more particularly, to a method of producing a transmissive screenused as a display screen of, for example, a projection television or amicrofilm reader and to the transmissive screen produced by this method.

BACKGROUND ART

[0002] In recent years, a rear projector using a liquid crystal lightvalve or a CRT as a large screen display has been drawing attention. Thedisplay displays an image by forming an image on a transmissive screenusing image light from an image projecting portion. This type oftransmissive screen is bright when an observer observes the image andhas predetermined very small lens members formed thereon so as toincrease the viewing angle.

[0003] As shown in FIG. 11, with regard to light distribution propertyof such a bright screen having a wide viewing angle, a viewing angle1101 which is wider in the horizontal direction than in the verticaldirection is preferred. This is because the viewing angle of a humanbeing is wider in the horizontal direction than in the verticaldirection. When the light distribution is made equal in the vertical andhorizontal directions, light is also distributed in the verticaldirection which is not really necessary with regard to the viewing angleof a human being, so that the brightness as a whole is reduced.

[0004] Representative examples of the structures of the transmissivescreen include the following:

[0005] {circle over (1)} A lenticular sheet including a lens portionformed by providing convex cylindrical lenses (semi-circular cylindricalconvex lenses) side by side. As shown in FIG. 9(a), in general, thelenticular sheet has a structure formed by forming both surfaces of thesheet into convex cylindrical lens surfaces 901, forming protrusions atboundary portions between the respective cylindrical lenses at one ofthe surfaces of the sheet (the surface from which image light 201exits), and forming a light-shielding layer (a black stripe havinglight-absorption property) 902 on the top portion of each of theprotrusions.

[0006] The lenticular sheet is obtained by carrying out a press-moldingoperation on a transparent thermoplastic resin sheet or by molding bothsurfaces of the resin sheet at the same time that molten extrusion iscarried out.

[0007] {circle over (2)} A planar lens having very small transparentballs arranged two dimensionally (disclosed in, for example, U.S. Pat.Nos. 2,378,252 and 3,552,822, and Japanese Utility Model RegistrationGazette No. 2513508). As shown in FIG. 10(a), in the planar lens, eachvery small transparent ball 1002 has of the order of 50% of its diameterembedded in and held by a light-incident side transparent layer 1001 andthe remaining 50% embedded in a light-exiting side light absorptionlayer 1003.

[0008] The planar lens is obtained by forming a sheet comprising atransparent layer, very small transparent balls, and a light-absorptionlayer, and, then, bonding it to a transparent substrate 1004.

[0009] However, such conventional transmissive screens have thefollowing problems.

[0010] In the lenticular lens, it is difficult to achieve a fine pitchwhen each of the above-described molding methods is performed onthermoplastic resin, so that, when the lenticular lens is used as ascreen of a rear projector, which, in recent years, has been providingincreasingly higher definition, there is a problem in that deteriorationof image quality occurs due to reduced resolution and production ofmoiré. In addition, a very small light diffusing material is usuallymixed in the inside portion of the lenticular lens in order to increasethe viewing angle in the vertical direction (a direction parallel to thelenticular lens, which is represented by reference numeral 903 in FIG.9(b)) in which the lenticular lens does not have optical power. Thisgives rise to the problem that image quality is deteriorated becausespeckles are produced due to the interference of image light caused bythe light-diffusing material. Further, both of the molding methodsperformed on the thermoplastic resin require large molding machines ordies having diagonals equal to or greater than 50 inches, which are ofthe same size as the screen of the rear projector, giving rise to theproblem that production costs become very high.

[0011] On the other hand, in the planar lens having very smalltransparent balls arranged two-dimensionally, as shown in FIG. 10(b) inwhich the planar lens is viewed from an image light incident side, deadspaces, which do not pass image light, are formed between the individualvery small balls 1002, so that the image light incident thereupon is nottransmitted to the observer side. In addition, it is very difficult toperform a minute filling operation completely with respect to the verysmall balls, so that the dead spaces increase in size. Further, sincethe thin light absorption layer 1003 remains at the observer-sidesurfaces of the very small transparent balls, light is absorbed. Due tothese three reasons, the problem that light transmittance of thetransmissive screen is low arises.

[0012] Since the increase in the viewing angle by the very small ballsis completely isotropic, light is also diffused in the verticaldirection, in which the viewing angle does not normally need to beincreased very much, to the same extent as in the horizontal direction.This gives rise to the problem of insufficient brightness when the imageis viewed from the front.

[0013] In general, the planar lens is produced by the step of forming asheet comprising a transparent layer, very small transparent balls, anda light absorption layer, and bonding the sheet to a transparentsubstrate. However, in the step of bonding the sheet to the transparentsubstrate, unevenness in the bonding occurs, so that the display of theimage becomes ununiform, and, by insufficient adhesiveness between thesheet and the transparent substrate, interfacial multiple reflectionoccurs, thereby giving rise to the problem of reduced resolution.

[0014] In order to overcome the above-described problems, it is anobject of the present invention to realize a method of producing at alow cost a transmissive screen which is bright, which has high contrastand resolution, and which is capable of displaying a high-quality imagewithout moiré and scintillation.

[0015] Disclosure of Invention

[0016] In order overcome the above-described problems, according to thepresent invention, there is provided a first form of a method ofproducing a transmissive screen having a structure includinglight-absorption-material patterns formed at locations corresponding tolocations of lens members, which are provided side by side on alight-transmissive substrate, and to locations of boundary portionsbetween the corresponding lens members, the method comprising the stepof forming the lens members or precursors thereof by causing very smalldrops of lens compositions to be discharged and to land near alight-transmission area on a surface of the light-transmissivesubstrate. Means for causing the very small drops of the lenscompositions to be discharged and to land is an inkjet recording head.Preferably, the inkjet recording head is a piezo jet recording head.

[0017] According to this form, the individual lens members, formed onthe surface of the transmissive screen, are formed by the discharging oflens compositions from an inkjet recording head, typified by, forexample, a piezo jet recording head, having the excellent feature offorming a very fine form with high precision over a large area.Therefore, very fine lens members can be produced. Consequently, it ispossible to provide a transmissive screen which provides excellentresolution and which does not have reduced image quality due to moiré.In addition, this method can be used in producing a transmissive screenby a manufacturing device including a mechanism that scans the piezo jetrecording head in the horizontal/vertical directions of the screen.Therefore, expensive manufacturing devices, such as large dies andmolding devices, are not required, thereby making it possible to reduceproduction costs.

[0018] In a second form of a method of producing a transmissive screenin accordance with the present invention, the surface form of each ofthe lens members is restricted by adjusting the surface tension andviscosity of each of the lens compositions, and the wettability of eachof the lens compositions and a surface which each of the lenscompositions contacts.

[0019] According to this form, a processing operation using a die is notrequired, so that the forms of the lens members can be controlled by asimple step, thereby making it possible to reduce production costs.

[0020] A third form of a method of producing a transmissive screen inaccordance with the present invention comprises the step of forming thelight-absorption-material patterns into the shape of a bank on a surfaceof the light-transmissive substrate prior to forming the lens membersand the precursors thereof by causing the very small drops of the lenscompositions to be discharged and to land near a light-transmissionportion of the bank-shaped light-absorption-material patterns.

[0021] According to this form, the lens resin compositions aredischarged onto the vicinity of the light-transmission portions of thebank-shaped light-absorption-material patterns in order to form the lensmembers, so that the light-absorption-material patterns and the lensmembers are aligned with high precision, thereby increasing the lighttransmittance of the transmissive screen.

[0022] In a fourth form of a method of producing a transmissive screenin accordance with the present invention, the surface of thelight-transmissive substrate on which the light-absorption-materialpatterns are formed is different from the surface where the lens membersare formed.

[0023] According to this form, it no longer becomes necessary toconsider the chemical reaction between thelight-absorption-material-pattern compositions and the lens membercompositions, thereby increasing the variety of materials from whichselection can be made, so that it is possible to provide a low-costtransmissive screen using low-cost materials.

[0024] In a fifth form of a method of producing a transmissive screen inaccordance with the present invention, the light-absorption-materialpatterns or precursors thereof are formed by causing very small drops oflight-absorption-material pattern compositions to be discharged and toland. Means for causing the very small drops of thelight-absorption-material pattern compositions to be discharged and toland is an inkjet recording head. Preferably, the inkjet recording headis a piezo jet recording head.

[0025] According to this form, since the light-absorption-materialpatterns and the lens members can be formed by the method of dischargingvery small drops and causing them to land, the production process issimplified, thereby making it possible to provide a low-costtransmissive screen.

[0026] In addition, since the light-absorption-material patterns areformed by discharging the light-absorption-material-pattern compositionsfrom the inkjet recording head, typified by, for example, a piezo jetrecording head, having the excellent feature of forming a very fine formwith high precision over a large area, it is possible to form very finelight-absorption-material patterns. Therefore, it is possible to providea transmissive screen which provides excellent resolution and which doesnot have reduced image quality due to moiré. Further, this method can beused to produce a transmissive screen by a manufacturing deviceincluding a mechanism that scans the piezo jet recording head in thehorizontal/vertical directions of the screen. Therefore, expensivemanufacturing devices, such as large dies and molding devices, are notrequired, thereby making it possible to reduce production costs.

[0027] A sixth form of a method of producing a transmissive screen inaccordance with the present invention comprises the step of restrictinga planar form of each of the lens members on the surface of thelight-transmissive substrate situated at the side where the lens membersare formed prior to forming the lens members or the precursors thereof,with the restricting operation being a chemical operation or arestricted form formation operation, which restrict spreading of thelens member compositions on the transparent substrate.

[0028] According to this form, since the forms of the lens members canbe controlled without using a die, it is possible to produce atransmissive screen having any viewing angle at a low cost.

[0029] In a seventh form of a method of producing a transmissive screenin accordance with the present invention, the step of restricting theplanar form of each of the lens members is the same as the step offorming the light-absorption-material patterns.

[0030] According to this form, it is possible to omit additional stepsof restricting the planar forms, so that the process can be simplified.

[0031] In an eighth form of a method of producing a transmissive screenin accordance with the present invention, adjacent lens members areformed of different lens member compositions. Preferably, the differentlens member compositions are adjusted so as to hardly mix with eachother.

[0032] According to this form, since the adjacent lens membercompositions may be those that do not mix easily with each other, it ispossible to reduce the distances between the adjacent lens members, sothat dead spaces become smaller. Therefore, it is possible to realize atransmissive screen having high light transmittance.

[0033] A form of a transmissive screen is produced by any one of themethods of producing a transmissive screen.

[0034] According to this form, the individual lens members, formed onthe surface of the transmissive screen, are formed by the discharging oflens compositions from an inkjet recording head, typified by, forexample, a piezo jet recording head, having the excellent feature offorming a very fine form with high precision over a large area.Therefore, very fine lens members can be produced. Consequently, it ispossible to provide a transmissive screen which provides excellentresolution and which does not have reduced image quality due to moiré.In addition, in this form, this method can be used in producing atransmissive screen by a manufacturing device including a mechanism thatscans the piezo jet recording head in the horizontal/vertical directionsof the screen. Therefore, expensive manufacturing devices, such as largedies and molding devices, are not required, thereby making it possibleto reduce production cost, and, thus, to provide a low-cost transmissivescreen.

[0035] In a second form of a transmissive screen of the presentinvention, spectral characteristics of the light-transmissive substrate,each of the lens members, and each of the light-absorption-materialpatterns are substantially smooth in the visible region.

[0036] According to this form, since the color of the display image canbe faithfully reproduced, it is possible to realize a transmissivescreen which can display a high-quality image.

[0037] In a third form of a transmissive screen of the presentinvention, the form of the bottom side of each of the lens members to beformed is substantially rectangular.

[0038] According to this form, since the bottom side forms of theindividual lens members are substantially rectangular, when theindividual lens members are subjected to a filling operation carried outwith close attention, dead spaces between the individual lens membersare not generated. Therefore, it is possible to realize a brighttransmissive screen having high light transmittance.

[0039] In a fourth form of the transmissive screen of the presentinvention, when the radius of curvature of each of the lens members,which is to be formed, in a horizontal direction of the transmissivescreen is RH and the radius of curvature of each of the lens members,which is to be formed, in a vertical direction of the transmissivescreen is RV, RH<RV.

[0040] According to this form, since the optical power of each lensmember in the horizontal direction is greater than the optical power ofeach lens member in the vertical direction, the viewing angle of thetransmissive screen in the horizontal direction can be made larger thanthe viewing angle of the transmissive screen in the vertical direction.Therefore, it is possible to adequately diffuse image light which haspassed through the transmissive screen in the proper direction inaccordance with the viewing angle characteristic of a human being.Consequently, a bright transmissive screen can be realized.

[0041] In a fifth form of a transmissive screen of the presentinvention, when the width of each of the lens members, which is to beformed, in a horizontal direction thereof is WH, and the width of eachof the lens members, which is to be formed, in a vertical directionthereof is WV, WH<WV.

[0042] According to this form, when the form of the surface of each lensmember is restricted by adjusting the surface tension and viscosity ofeach of the lens compositions and the wettability of each of the lenscompositions and a surface which each of the lens compositions contacts,the radius of curvature of the larger-width portion of each lens memberbecomes large and that of the smaller-width portion of each lens memberbecomes small. When this is seen from the point of view of opticalpower, the smaller radius of curvature corresponds to the larger opticalpower. Therefore, by causing the horizontal-direction width of each lensmember to be smaller than the vertical-direction width thereof as inthis form, the optical power in the horizontal direction becomes largerthan that in the vertical direction, so that the viewing angle of thetransmissive screen in the horizontal direction can be made larger thanthat of the transmissive screen in the vertical direction. Therefore, itis possible to adequately diffuse image light which has passed throughthe transmissive screen in the proper direction in accordance with theviewing angle characteristic of a human being. Consequently, a brighttransmissive screen can be realized.

[0043] In a sixth form of a transmissive screen of the presentinvention, the distances between adjacent landing target locations ofthe lens compositions are not uniform in a plane of the transmissivescreen.

[0044] According to this form, since the lens members are not disposedat the transmissive screen in a regular manner, it is possible toimprove the quality of a projected image with reduced moiré.

[0045] In a seventh form of a transmissive screen of the presentinvention, the distances between the adjacent landing target locationsof the lens compositions in a horizontal direction and those in avertical direction are different. Preferably, when the distances in thehorizontal direction are PH and those in the vertical direction are PV,PH>PV. More preferably, when the diameter of a single lens member is SP,the distances between the adjacent landing target locations of the lenscompositions are such that PH>SP>PV.

[0046] According to this form, it is possible to fuse adjacent lensmembers in the vertical direction. The resulting compound lens memberobtained is such that its vertical-direction radius of curvature islarger than the horizontal-direction radius of curvature, so that it ispossible for the horizontal-direction viewing angle of the transmissivescreen to be greater than the vertical-direction viewing angle of thetransmissive screen.

[0047] There is provided a ninth form of a method of producing atransmissive screen having a structure includinglight-absorption-material patterns formed on locations corresponding tolocations of lens members, which are provided side by side on alight-transmissive substrate, and to locations of boundary portionsbetween the corresponding lens members. The method comprises the step offorming volume-type phase devices or precursors thereof by causing verysmall drops of volume-type phase device compositions to be dischargedand to land, with the volume-type phase devices having random phasedistributions being provided side by side on a surface of thelight-transmissive substrate where the lens members are formed or theback side of the surface. Means for causing the very small drops of thevolume-type phase device compositions to be discharged and to land is aninkjet recording head. Preferably, the inkjet recording head is a piezojet recording head.

[0048] According to this form, volume-type phase devices having randomphase distribution are provided side by side on the back side of alens-formation surface of the light-transmissive substrate. Sinceinterference is reduced by randomly disturbing a wave surface of imagelight, speckles can be considerably reduced. In addition, since thevolume-type phase devices are formed by using an inkjet recording head,typified by a piezo jet recording head, production costs can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

[0049]FIG. 1 illustrates the steps of a first embodiment of a method ofproducing a transmissive screen in accordance with the presentinvention.

[0050]FIG. 2 is a plan view and a sectional view of the structuralelements used in the first embodiment.

[0051]FIG. 3 illustrates the light distribution function of a lensmember used in the first embodiment.

[0052]FIG. 4 illustrates the steps of a second embodiment of a method ofproducing a transmissive screen in accordance with the presentinvention.

[0053]FIG. 5 illustrates the steps of a third embodiment of a method ofproducing a transmissive screen in accordance with the presentinvention.

[0054]FIG. 6 illustrates a gap between adjacent landing target locationsand the planar form of a lens member to be formed in the thirdembodiment.

[0055]FIG. 7 illustrates a gap between some other adjacent landingtarget locations and the planar form of the lens member to be formed inthe third embodiment.

[0056]FIG. 8 illustrates the steps of a fourth embodiment of a method ofproducing a transmissive screen in accordance with the presentinvention.

[0057]FIG. 9 is a structural view of a lenticular lens sheet.

[0058]FIG. 10 is a structural view of a planar lens.

[0059]FIG. 11 illustrates the light distribution of a transmissivescreen. Best Mode for Carrying Out the Invention

[0060] Hereunder, with reference to the drawings and the like, adetailed description will be given by providing embodiments of thepresent invention.

FIRST EMBODIMENT OF A METHOD OF PRODUCING A TRANSMISSIVE SCREEN

[0061]FIG. 1 illustrates a generalization of the steps used in the firstembodiment.

[0062] First, as shown in FIG. 1(a), a light-absorption material 102 issubjected to a patterning operation to be a desired form on alight-transmissive substrate 101. It is desirable that thelight-transmissive substrate 101 have a substantially uniform lighttransmittance property over the entire visible region and that thislight transmittance be high. The light-transmissive substrate 101 may bemade to have light diffusion property by diffusing very small,diffusible particles in the substrate or by forming the surface thereofas a diffusing surface. In addition, it is preferable to form thelight-transmissive substrate 101 with a rigid material that can maintainsmoothness when it is incorporated in a rear projector. Examples of sucha rigid material are transparent glass substrate and acrylic substrate,but are not limited thereto.

[0063] Similarly, it is preferable for the light-absorption material 102to be a material having a substantially uniform absorption property overthe entire visible region, and for the light transmittance of thematerial to be low. The characteristics of the material are selected byconsidering various characteristics from the viewpoints of thepatterning method used and chemical interactions between lens members.

[0064] Examples of methods of patterning the light-absorption material102 are photolithography and various other printing techniques, and amethod in which a light-absorption material compositions are dischargedonto selected locations from an inkjet recording head, typified by apiezo jet recording head, but are not limited to a particular method.However, of these methods, the most preferable method is the methodusing a piezo jet recording head because, economically speaking, itallows formation of a very fine form over a large area with highprecision.

[0065] The light-absorption material 102 is formed at locations selectednear boundary portions of individual lens members formed in a laterstep. FIG. 2(a) illustrates the state of arrangement of thelight-absorption material 102 in plan view. FIG. 2(a) is a plan view inwhich the transmissive screen used in the embodiment is seen from a sidefrom which image light is incident, with a solid line indicatingindividual lens members 105 and a dotted line indicating thelight-absorption material 102. The light-absorption material 102 isprovided near the boundary portions of the lens members 105, and openportion 107 passing light rays are formed near the center portions ofthe lens members 105.

[0066]FIG. 2(b) is a cross-sectional structure of the transmissivescreen and an image light path, in a section taken along line H-H′ ofFIG. 2(a). Image light 201 incident upon the lens members 105 isrefracted by the lens members 105, passes through the open portions 107,and is transmitted towards an observer. On the other hand, outside light202 from, for example, an illumination lamp disposed in the space at theobserver side is such that most of it is absorbed by thelight-absorption material 102. Therefore, even if the illuminationintensity in the space at the observer side is high, it is possible toenjoy observing a sharp black image having high contrast.

[0067] Here, when a top side width 203 of the light-absorption material102 is large, the proportion by which the image light 201 is absorbedbecomes large. Therefore, in order to increase transmittance of theimage light, it is preferable to make the top side width 203 as small aspossible.

[0068] On the other hand, when a bottom side width 204 of thelight-absorption material 102 is made as large as possible, the outsidelight absorption effect is high. From the above, it is desirable thatthe cross-sectional form of the light-absorption material 102 be atapering form so as to widen towards the light-transmissive substrate101.

[0069] In order to make the bottom side width 204 of thelight-absorption material 102 as large as possible, it is desirable forthe open portions 107 to be disposed near the focal points of the lensmembers 105. From this viewpoint, the height of the light-absorptionmaterial 102 is determined.

[0070] Next, as shown in FIG. 1(b), lens member compositions 108 aredischarged into spaces bounded by the light-absorption material 102 froma piezo jet recording head 103 in order to form lens precursors 104.

[0071] The piezo jet recording head 103 discharges the supplied lensmember compositions from its nozzle by a known inkjet method. Tofacilitate understanding of the embodiment, only one head is shown, butit is obvious that productivity can be increased by disposing aplurality of heads side by side in order to discharge lens membercompositions over a large area and by performing scanning of theplurality of heads in the entire plane of the light-transmissivesubstrate 101.

[0072] The spaces bounded by the light-absorption material 102 arefilled with drops 108 of the discharged lens member compositions, andthe lens member precursors 104 whose surfaces have been formed into theforms of lenses are formed. The forms of the surfaces of the precursors104 are determined primarily by the viscosities and surface tensions ofthe lens member compositions and the wettability of the lens membercompositions with respect to the light-absorption material. From theseviewpoints, the chemical composition of the light-absorption materialand the lens member compositions are adjusted.

[0073] Although, in FIG. 1(b), a boundary width 109 between the adjacentprecursors 104 is drawn extremely small, from the viewpoint of formingthe forms of the surfaces of the precursors 104, the boundary width 109may be large. However, when the boundary widths 109 are made too large,the transmittance of the image light is reduced. From this viewpoint, itis effective to use a method in which different types of compositionsthat do not mix easily with each other are used for the lens membercompositions that are discharged from adjacent nozzles 103 a and 103 b.This is because, when this method is used, even if the lens membercompositions spread, the boundaries between the lens members arenaturally formed as a result of the lens member compositions coming intocontact with each other. For the lens member compositions that do notmix easily with each other, a hydrophilic composition may be used forone of the lens member composition types and a hydrophobic compositionmay be used for the other type of lens member composition. However thelens member composition types which may be used are not limited thereto.

[0074] Next, by a post-processing step shown in FIG. 1 (c), theprecursors 104 are formed into the lens members 105 having desiredcharacteristics. An example of the post-processing operation may be ahardening reaction by, for example, irradiation of light or heating.However, the type of post processing operation is not limited thereto,so that various other types of post-processing operations may be carriedout based on the chemical properties of the lens member compositionsused. The post processing step includes not only a hardening reaction,but also post-processing for increasing light transmittance,post-processing for forming the precursors 104 into more desirableforms, etc. If, after dropping the lens member composition liquids, achemical change occurs as time passes even without carrying out anyprocessing operation and a desired characteristic is obtained afterpassage of a certain amount of time, the post-processing step isomitted. An example of such a case is that compositions which reactchemically by mixing two liquids or anaerobic compositions are used asthe lens member compositions.

[0075] The following step is carried out to give the lens membersadditional characteristics. FIG. 1 (d) shows an example in which atransparent protective layer 106 is provided at the surface of each lensmember in order to increase the mechanical strength of the transmissivescreen. Here, additional characteristics include, in addition tomechanical strength, increased chemical durability by, for example,anaerobic processing, and the increased optical characteristics basedon, for example, AR coating.

[0076]FIG. 3 illustrates the structure of a lens member used in theembodiment.

[0077]FIG. 3(a) shows the bottom surface form (the form of the surfacethat contacts the light-transmissive substrate 101) of the lens member105, in which, when its horizontal-direction width 301 is WH and itsvertical-direction width 302 is WV, WH<WV. Such a bottom surface form isdetermined by the planar form of the light-absorption material 102.

[0078] The form of the surface of the lens member 105 is determinedprimarily by the viscosity and surface tension of the lens membercomposition and the wettability of the lens member composition withrespect to the light-absorption material, so that when ahorizontal-direction radius of curvature 303 of the surface of the lensmember 105 along line H-H′ shown in FIG. 3(a) is RH and avertical-direction radius of curvature 304 of the surface of the lensmember 105 taken along line V-V′ is RV, RH<RV.

[0079]FIG. 3(b) is sectional view of the lens member 105 taken alongline H-H′, and FIG. 3(c) is a sectional view of the lens member 105taken along line V-V′. As mentioned above, since RH is smaller than RV,the optical power of the lens member 105 in the H-H′direction shown inFIG. 3(b) becomes large. Spreading of the image light 201 in thisdirection after it has exited from the light-transmissive substrate 101is OH. In contrast, the optical power of the lens member 105 in the V-V′direction becomes smaller. When spreading of the image light 201 in thisdirection after it has exited from the light-transmissive substrate 101is defined as θV, θH>θV, so that it becomes possible to control theviewing angle to be suitable for the viewing-angle characteristics of ahuman being, which has been described with reference to FIG. 11.

[0080] (Second Embodiment of a Method of Producing a TransmissiveScreen)

[0081]FIG. 4 illustrates a generalization of the steps used in thesecond embodiment of the present invention.

[0082] As shown in FIG. 2(a), on the light-transmissive substrate 101,lens form restriction patterns 401 are formed by patterning at selectedlocations near the boundary portions of the individual lens members thatare formed in a later step. Examples of the method of forming the lensform restriction pattern 401 by patterning are photolithography andvarious other printing techniques, and a method in which alight-absorption material compositions are discharged onto selectedlocations from an inkjet recording head, typified by a piezo jetrecording head, but are not limited to a particular method. However, ofthese methods, the most preferable method is the method using a piezojet recording head because, economically speaking, it allows formationof a very fine form over a large area with high precision.

[0083] It is preferable that, over the entire visible region, the lighttransmittance property of the lens form restriction patterns 401 besubstantially smooth, and that the light transmittance be high. Bymaking use of its chemical properties at its surface, the lens formrestriction patterns 401 restrict the forms of the lens members that areformed in a later step. For example, the pattern surface may have ahydrophilic property and the composition of each lens member may have ahydrophobic property. Examples are not limited to these.

[0084] A film 402 for a light-absorption material is formed at the backside of the portion of the light-transmissive substrate 101 where thelens form restriction patterns 401 are formed.

[0085] The film 402 for the light-absorption material is aphotosensitive film, and portions thereof upon which light has impingedand portions thereof upon which light has not impinged have differentchemical and optical properties.

[0086] Typical examples of such a film are a positive photosensitiveadhesive which exhibits the property of losing its adhesiveness by beingexposed, and chromarin film (produced by E.I. Du Pont de Neumours Inc.),but are not limited thereto.

[0087] Next, as shown in FIG. 4(b), from the piezo jet recording head103, lens member compositions 108 are discharged onto the surface of thetransparent substrate bounded by the lens form restriction patterns 401in order to form the lens precursors 104. This step has been describedin detail in the first embodiment, and the description thereof isomitted.

[0088] Next, as shown in FIG. 4(c), from the lens member 105 side, thelight-absorption-material film 402 is radiated with an electromagneticwave 403 having a wavelength that causes photosensitive reaction, and,by each lens member 105, the electromagnetic wave 403 converges near thelight-absorption-material film 402 in order to cause aphotosensitization action to occur at selected locations of thelight-absorption-material film 402.

[0089] In this step, each lens member 105 may be in the lens precursorstate. When a hardening reaction, a light transmittance increasingreaction, etc., are caused to occur by the electromagnetic wave 403, sothat a change to a more preferable state can be achieved, the step canbe simplified, which is preferable.

[0090] Portions 404 where a photosensitization reaction occured atselected locations of the light-absorption-material film 402 aretransparent portions, so that image light that has converged by eachlens member 105 passes therethrough. On the other hand, portions 405which have not been exposed exhibit light absorptivity, so that itabsorbs outside light.

[0091] When the aforementioned chromarin film is used, the portions 404where a photosensitive reaction has occurred lose their adhesiveness,and the adhesiveness of the portions 405 that have not been exposedremains. Therefore, in a post-processing step (not shown), for example,powder having light-absorption property is scattered on thelight-absorption-material film 402. When this is selectively made toadhere to the portions 405 which have not been exposed, it is possibleto form light-absorption-material patterns 406 at selected locations.

[0092] As is clear from FIG. 4(c), in the embodiment, the thickness ofthe light-transmissive substrate 101 is set so as to be substantiallythe same as the light converging distance of each lens member 105. Thelight converging distance is the distance substantially equal to f×n,when the focal length of each lens member 105 in air is f and therefractive index of the light-transmissive substrate 101 is n.

[0093] (Third Embodiment of a Method of Producing a Transmissive Screen)

[0094]FIG. 5 illustrates a generalization of the steps used in the thirdembodiment of the present invention.

[0095] First, as shown in FIG. 5(a), a surface treatment layer 501having high transparency is uniformly formed on the light-transmissivesubstrate 101. The surface treatment layer 501 has liquid repellencywith respect to each of the lens member compositions to be discharged onthis layer. In other words, when each of the lens member compositions isa hydrophilic material, it has water repellency, whereas, when each lensmember composition is a lipophilic material, it is hydrophilic.

[0096] The surface-treatment layer 501 is formed by various thin filmformation technologies, such as spin coating, dipping, printing,spraying, vapor deposition, sputtering, or forming of a self-organizingfilm, in accordance with the physical properties of the material of thesurface-treatment layer 501.

[0097] Of these technologies, the thin film formation technology used toform a self-organizing film is suitable for the present inventionbecause the liquid repellency of the self-organizing film can be easilycontrolled and the formation of the self-organizing film does notrequire a special device.

[0098] The self-organizing film is a molecular film containing organicmolecules. The organic molecules each contain a functional group whichcan combine with the light-transmissive substrate 101; a functionalgroup, such as a lyophilic group or a liquid-repellent group, providedopposite to the previous functional group, for modifying the nature ofthe surface of the light-transmissive substrate 101 (that is,controlling the surface energy); and a normal carbon chain whichcombines with these functional groups or a carbon chain having a portionthereof branched. These organic molecules combine with thelight-transmissive substrate 101 and are self-organized in order to forma molecular film, such as a monomolecular film. The self-organizing filmcontains a bonding functional group that can react with constituentmolecules of the light-transmissive substrate 101, and otherstraight-chain molecules. It is a film in which compounds having veryhigh orientation properties by interaction between the straight-chainmolecules are aligned. Since the self-organizing film is formed byaligning single molecules, it is a uniform film on the molecular level.In other words, since the same molecules are positioned at the surfaceof the film, the surface of the film is uniform and can be provided withsurface properties, such as excellent liquid repellency and a lyophilicproperty.

[0099] Examples of the compounds making up the self-organizing filminclude alkylsilanes containing an alkyl group or fluoroalkylsilanessuch as heptadecafluorotetrahydrodecyltriethoxysilane ortrifluoropropyltrimethoxysilane. The self-organizing film is disclosedin detail in, for example, “An Introduction Ultra-thin Organic Films,”Ulman, Academic Press.

[0100] When the surface-treatment layer 501 is formed using theself-organizing film, any one of the aforementioned material compoundsand the light-transmissive substrate 101 are placed in the same sealedcontainer. When the temperature is ordinary temperature, thesurface-treatment layer 501 is formed by leaving it for a few days. Bymaintaining the whole sealed container at a temperature of the order of100° C., the surface-treatment layer 501 can be formed in a time of theorder of three hours. In this way, since the step of forming thesurface-treatment layer 501 using a self-organizing film is very simpleand does not require a special device, this step is particularlysuitable for producing a large transmissive screen.

[0101] A light-absorption film 502 is formed on the back side of thesurface of the light-transmissive substrate 101 where thesurface-treatment layer 501 is formed. The light-absorption layer 502 isformed of a material which has a smooth light transmittance in thevisible region and which has high absorptivity with respect to laserlight. In accordance with the physical properties of the material of thelight-absorption layer 502, the light-absorption layer 502 is formed byvarious thin film formation technologies, such as spin coating, dipping,printing, spraying, vapor deposition, sputtering, or forming of aself-organizing film.

[0102] Then, as shown in FIG. 5(b), from the piezo jet recording head103, lens member compositions 108 are discharged onto the surface of thelight-transmissive substrate 101 where the surface-treatment layer 501is formed, thereby forming the lens precursors 104. However, since,unlike the first and second embodiments, there are no structures orpatterns that separate adjacent lenses, special considerations arerequired to form individual lens members separately.

[0103]FIG. 6(a) shows the relationship between the diameter of a lensprecursor 104 and a landing target location 601 of the lens membercomposition on the light-transmissive substrate 101. After the lensmember compositions 108 have landed near the landing target locations601, they runs out and spread by contact angles determined by therelationship between their wettability with respect to thesurface-treatment layer 501, thereby forming the lens precursors 104having curvatures determined by the surface tensions of the lens membercompositions 108. The planar forms of the precursors 104 aresubstantially circular having diameters SP with the correspondinglanding target locations 601 being the substantial centers thereof.Therefore, as shown in FIG. 6(b), when an interval P between adjacentlanding target locations 601 is such that P>SP, individual lensprecursors 104 that are separated from each other can be formed. When Pis excessively larger than SP, the dead spaces between the lensprecursors 104 become large, thereby reducing the light transmittance ofthe transmissive screen, so that this is not preferable. In addition, asshown in FIG. 6(c), when the interval P between adjacent landing targetlocations 601 is set so that P<SP, after the lens member compositions108 have landed, the adjacent lens member compositions coalesce, so thatseparate individual lens precursors cannot be formed.

[0104] Therefore, when a pitch PN between the adjacent nozzles 103 a and103 b of the piezo jet recording head 103 is such that PN>SP, it ispossible to separately form adjacent individual lens precursors 104.Although the example of adjusting the pitch PN between the adjacentnozzles has been described here, it is obvious that the same advantagescan be obtained by suitably controlling a scanning pitch of the piezojet recording head 103 by setting the pitch PN between the adjacentnozzles to be a distance different from the pitches between the adjacentlens precursors 104.

[0105] In addition, it is possible to control the viewing angle of thetransmissive screen by positively fusing the adjacent lens precursors104 into an integral structure.

[0106]FIG. 7(a) illustrates the arrangement of nine adjacent landingtarget locations 601. A horizontal-direction pitch PH between adjacentlanding target locations 601 is set so that PH>SP, while avertical-direction pitch PV is set so that PV<SP. Each lens membercomposition 108 is discharged onto and lands on each of these landingtarget locations 601, so that, as shown in 7(b), the lens precursors 104having planar forms that are individually and separately formed in thehorizontal direction and having fused forms in the vertical directionare formed. As regards the curvature of each lens member obtained fromits corresponding lens precursor 104, when the horizontal-directionradius of curvature is RH and the vertical-direction radius of curvatureis RV, RH<RV. As described in the first embodiment, the spreading ofimage light that has passed through each lens member is wider in thehorizontal direction in conformity with the viewing angle characteristicof a human being, so that it possesses a viewing angle characteristicthat is narrow in the vertical direction.

[0107] The pitches between the landing target locations 601 do not haveto be uniform over the entire transmissive screen, so that they can befreely set based on desired characteristics. For example, with thevertical-direction pitches made variable, the number of lens membercompositions that are fused can be controlled in order to adjust thevertical viewing angle or the regularity of the pitches in thehorizontal and vertical directions can be reduced in order to reducemoiré that occurs due to the interaction between the image light and theoptically regular patterns of the lens members.

[0108] Next, as shown in FIG. 5(c), laser light 503 having an intensityequal to or greater than a threshold value that causes in its convergedstate fusion/evaporation or abrasion of the material of thelight-absorption layer 502 is caused to impinge from the lens member 105side, and to converge near the light-absorption layer 502.Fusion/evaporation or abrasion is caused to occur at selected locationsof the light-absorption layer 502 near the converging portion of thelaser light 503, thereby forming open portions 504. In this step, eachlens member 105 may be in a lens precursor state, and if, for example, ahardening reaction or a light transmittance increasing reaction iscaused to occur by the laser light 503, so that changes to a morepreferable state are achieved, the step can be simplified, which ispreferable.

[0109] The open portions 504 of a light-absorption-material pattern 506pass the image light that has been converged by each lens member 105.Unopen portions 505 exhibit light absorption, so that they absorboutside light.

[0110] As is well known, it is necessary for the laser light to have ahigh energy value in order to cause fusion/evaporation or abrasion tooccur at the laser light absorption material. Examples of lasers whichproduce such laser light are an excimer laser using, for example, XeF;an Nd:YAG laser; a Ti:Al₂O₃ laser and a laser producing light obtainedafter harmonic and wavelength changes thereof have been made; and a dyelaser. In order to irradiate the large-area light-transmissive substrate101 with intense laser light over the entire area thereof, scanning theentire area with a small-area laser light spot by light-deflecting meansis effective from the viewpoints of preventing the laser device frombecoming large in size and complicated.

[0111] (Fourth Embodiment of a Method of Producing a TransmissiveScreen)

[0112]FIG. 8 illustrates a generalization of the steps used in thefourth embodiment.

[0113] As shown in FIG. 8(a), from the piezo jet recording head 103, avolume-type phase device composition 801 is discharged onto the backside of the surface of the light-transmissive substrate 101 where thelight-absorption-material pattern 102 and the lens members 105 havealready been formed, thereby forming a volume-type phase deviceprecursor 802.

[0114] The volume-type phase device precursor 802 is formed of amaterial having high light transmittance that is substantially smoothover the entire visible region, and has a random form and arrangementdistribution, which are determined in accordance with the extent towhich the coherence of image light is reduced. Such a form andarrangement distribution are provided by randomly changing the liquidamount of the volume-type phase device composition 801 discharged fromthe piezo jet recording head 103 or by randomly changing the scanningdirection and scanning amount of the piezo jet recording head 103.

[0115] Next, as shown in FIG. 8(b), the volume-type phase device 803 isprovided with more preferable characteristics by, for example, hardeningthe volume-type phase device precursor 802 by light irradiation,heating, or the like.

[0116] In this way, by forming the volume-type phase device 803 on theback side of the surface of the light-transmissive substrate 101 wherethe lens members 105 are formed, the coherence of image light can bereduced, so that it is possible to enjoy observing a high-quality imagehaving few speckles.

[0117] (Fifth Embodiment of a Method of Producing a Transmissive Screen)

[0118] Although in the first to fourth embodiments the lens membercompositions or the volume-type phase device composition have beendescribed by referring to optically transparent materials which can bedischarged by the piezo jet recording head as an example, it is possibleto mix very small particles having light diffusing property in order tofurther increase the light diffusion action of each lens member.Examples of such very small particles are glass beads, styrene beads,and acrylic beads, which have average particle diameters of the order ofa few microns to 20 microns. However, the types of very small particlesare not limited to these examples.

[0119] The above-described lens member compositions are applicable toany one of the first to fourth embodiments, and are effective structuralmaterials for adjusting the viewing angle of the transmissive screen.

[0120] (Modifications)

[0121] The present invention is not limited to the above-describedembodiments, so that various modifications and changes may be madewithin a scope not departing from the gist of the present invention.

[0122] For example, although the piezo jet recording head has beenreferred to as the head member which discharges drops of, for example,lens compositions, other inkjet recording heads having similar functionsmay be used. A typical example is a bubble jet recording head.

[0123] In addition, although the bottom surface of each lens member hasbeen described as having a rectangular form, it may have a circularform, an elliptical form, or an indeterminate form.

[0124] Further, although the light-absorption-material patterns havebeen described as having tapered forms in cross section, they may haverectangular parallelepiped forms or curved forms in cross section.

[0125] Industrial Applicability

[0126] As described in detail above, according to the present invention,there is provided a method of producing a transmissive screen having astructure including light-absorption-material patterns formed atlocations corresponding to locations of lens members, which are providedside by side on a light-transmissive substrate, and corresponding tolocations of boundary portions between the lens members. In this method,very small droplets of lens compositions are discharged onto and land onthe light-transmissive substrate. By the droplets of the lenscompositions, the lens members or precursors thereof are formed. Thismakes it possible to realize at a low cost a bright transmissive screenwhich has high contrast and which can display a high-quality imagehaving reduced moiré and few speckles.

What is claimed is:
 1. A method of producing a transmissive screenhaving a structure including light-absorption-material patterns formedat locations corresponding to locations of lens members, which areprovided side by side on a light-transmissive substrate, and tolocations of boundary portions between the corresponding lens members,the method comprising the step of forming the lens members or precursorsthereof by causing very small drops of lens compositions to bedischarged and to land near a light-transmission area on a surface ofthe light-transmissive substrate.
 2. A method of producing atransmissive screen according to claim 1, wherein means for causing thevery small drops of the lens compositions to be discharged and to landis an inkjet recording head.
 3. A method of producing a transmissivescreen according to claim 2, wherein the inkjet recording head is apiezo jet recording head.
 4. A method of producing a transmissive screenaccording to claim 1, wherein the surface form of each of the lensmembers is restricted by adjusting the surface tension and viscosity ofeach of the lens compositions, and the wettability of each of the lenscompositions and a surface which each of the lens compositions contacts.5. A method of producing a transmissive screen according to claim 1,comprising the step of forming the light-absorption-material patternsinto the shape of a bank on a surface of the light-transmissivesubstrate prior to forming the lens members or the precursors thereof bycausing the very small drops of the lens compositions to be dischargedand to land near a light-transmission portion of the bank-shapedlight-absorption-material patterns.
 6. A method of producing atransmissive screen according to claim 1, wherein the surface of thelight-transmissive substrate on which the light-absorption-materialpatterns are formed is different from the surface where the lens membersare formed.
 7. A method of producing a transmissive screen according toany one of claims 1 to 6, wherein the light-absorption-material patternsor the precursors thereof are formed by causing very small drops oflight-absorption-material pattern compositions to be discharged and toland.
 8. A method of producing a transmissive screen according to claim7, wherein means for causing the very small drops of thelight-absorption-material pattern compositions to be discharged and toland is an inkjet recording head.
 9. A method of producing atransmissive screen according to claim 8, wherein the inkjet recordinghead is a piezo jet recording head.
 10. A method of producing atransmissive screen according to any one of claims 1 to 9, comprisingthe step of restricting a planar form of each of the lens members on thesurface of the light-transmissive substrate situated at the side wherethe lens members are formed prior to forming the lens members or theprecursors thereof, with the restricting operation being a chemicaloperation or a restricted form formation operation, which restrictspreading of the lens member compositions on the transparent substrate.11. A method of producing a transmissive screen according to claim 10,wherein the step of restricting the planar form of each of the lensmembers is the same as the step of forming the light-absorption-materialpatterns.
 12. A method of producing a transmissive screen according toany one of claims 1 to 11, wherein adjacent lens members are formed ofdifferent lens member compositions.
 13. A method of producing atransmissive screen according to claim 12, wherein the different lensmember compositions are adjusted so as to hardly mix with each other.14. A transmissive screen produced by the method of producing atransmissive screen of any one of claims 1 to
 13. 15. A transmissivescreen according to claim 14, wherein spectral characteristics of thelight-transmissive substrate, each of the lens members, and each of thelight-absorption-material patterns are substantially smooth in thevisible region.
 16. A transmissive screen according to claim 14, whereinthe form of the bottom side of each of the lens members to be formed issubstantially rectangular.
 17. A transmissive screen according to claim14, wherein, when the radius of curvature of each of the lens members,which is to be formed, in a horizontal direction of the transmissivescreen is RH and the radius of curvature of each of the lens members,which is to be formed, in a vertical direction of the transmissivescreen is RV, RH<RV.
 18. A transmissive screen according to claim 17,wherein, when the width of each of the lens members, which is to beformed, in a horizontal direction thereof is WH, and the width of eachof the lens members, which is to be formed, in a vertical directionthereof is WV, WH<WV.
 19. A transmissive screen according to claim 14,wherein the distances between adjacent landing target locations of thelens compositions are not uniform in a plane of the transmissive screen.20. A transmissive screen according to claim 19, wherein the distancesbetween the adjacent landing target locations of the lens compositionsin a horizontal direction and those in a vertical direction aredifferent.
 21. A transmissive screen according to claim 20, wherein,when the distances between the adjacent landing target locations of thelens compositions in the horizontal direction are PH and those in thevertical direction are PV, PH>PV.
 22. A transmissive screen according toclaim 21, wherein, when the diameter of the single lens member is SP,the distances between the adjacent landing target locations of the lenscompositions are such that PH>SP>PV.
 23. A method of producing atransmissive screen having a structure includinglight-absorption-material patterns formed on locations corresponding tolocations of lens members, which are provided side by side on alight-transmissive substrate, and to locations of boundary portionsbetween the corresponding lens members, the method comprising the stepof forming volume-type phase devices or precursors thereof by causingvery small drops of volume-type phase device compositions to bedischarged and to land, with the volume-type phase devices having randomphase distributions being provided side by side on a surface of thelight-transmissive substrate where the lens members are formed or theback side of the surface.
 24. A method of producing a transmissivescreen according to claim 23, wherein means for causing the very smalldrops of the volume-type phase device compositions to be discharged andto land is an inkjet recording head.
 25. A method of producing atransmissive screen according to claim 24, wherein the inkjet recordinghead is a piezo jet recording head.